David Anderson, the independent reviewer of terrorism legislation, has agreed to lead the independent review into the Investigatory Powers Bill and will report over the summer on the spooks' activities towards collecting bulk information.

Burnham described the letter as "extremely encouraging", the BBC reported, and said: "Her commitment to an independent review of the case for bulk powers is a major concession but the right thing to do and something which will build trust in this process."

In today's Parliamentary debate, Burnham will tell the House of Commons: "As the Home Secretary knows, we share her goal of putting an updated law into the Statute Book governing the use of investigatory powers and giving the Police and the security services the powers to do their job in the digital age."

However, he will add, Labour continues "to have serious concerns about the Bill as currently drafted. It does not yet contain sufficiently strong safeguards and human rights protections."

According to the BBC, a Home Office spokesperson claimed: "The Home Secretary has always been clear she will listen to the constructive views of politicians from all sides of the House to ensure the passage of this important Bill. The Government will be bringing forward amendments at Report Stage."